LeetCode

LeetCode Topics

Array

0001-two-sum
0011-container-with-most-water
0015-3sum
0016-3sum-closest
0018-4sum
0031-next-permutation
0036-valid-sudoku
0037-sudoku-solver
0041-first-missing-positive
0051-n-queens
0073-set-matrix-zeroes
0075-sort-colors
0090-subsets-ii
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0139-word-break
0167-two-sum-ii-input-array-is-sorted
0229-majority-element-ii
0238-product-of-array-except-self
0289-game-of-life
0391-perfect-rectangle
0442-find-all-duplicates-in-an-array
0486-predict-the-winner
0491-non-decreasing-subsequences
0494-target-sum
0594-longest-harmonious-subsequence
0643-maximum-average-subarray-i
0713-subarray-product-less-than-k
0729-my-calendar-i
0731-my-calendar-ii
0810-valid-tic-tac-toe-state
0825-max-increase-to-keep-city-skyline
0880-rectangle-area-ii
0925-construct-binary-tree-from-preorder-and-postorder-traversal
0929-groups-of-special-equivalent-strings
0940-fruit-into-baskets
0952-word-subsets
1016-subarray-sums-divisible-by-k
1043-grid-illumination
1046-max-consecutive-ones-iii
1138-grumpy-bookstore-owner
1184-car-pooling
1253-sort-the-matrix-diagonally
1310-watering-plants
1324-where-will-the-ball-fall
1342-queens-that-can-attack-the-king
1386-shift-2d-grid
1445-number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold
1477-product-of-the-last-k-numbers
1478-maximum-number-of-events-that-can-be-attended
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
1572-subrectangle-queries
1711-find-valid-matrix-given-row-and-column-sums
1787-sum-of-absolute-differences-in-a-sorted-array
1851-maximum-number-of-events-that-can-be-attended-ii
1972-rotating-the-box
1983-maximum-population-year
1995-finding-pairs-with-a-certain-sum
2078-maximum-compatibility-score-sum
2080-check-if-move-is-legal
2132-convert-1d-array-into-2d-array
2205-find-good-days-to-rob-the-bank
2211-k-radius-subarray-averages
2228-watering-plants-ii
2244-number-of-laser-beams-in-a-bank
2270-find-all-lonely-numbers-in-the-array
2290-removing-minimum-number-of-magic-beans
2388-replace-elements-in-an-array
2398-check-if-matrix-is-x-matrix
2465-shifting-letters-ii
2504-find-all-good-indices
2691-count-vowel-strings-in-ranges
2696-the-number-of-beautiful-subsets
2714-left-and-right-sum-differences
3034-points-that-intersect-with-cars
3215-matrix-similarity-after-cyclic-shifts
3299-find-the-maximum-number-of-elements-in-subset
3335-minimum-operations-to-write-the-letter-y-on-a-grid
3338-count-submatrices-with-top-left-element-and-sum-less-than-k
3398-make-a-square-with-the-same-color
3420-find-occurrences-of-an-element-in-an-array
3461-find-the-minimum-area-to-cover-all-ones-i
3743-reschedule-meetings-for-maximum-free-time-i

Hash Table

0001-two-sum
0012-integer-to-roman
0030-substring-with-concatenation-of-all-words
0036-valid-sudoku
0037-sudoku-solver
0041-first-missing-positive
0073-set-matrix-zeroes
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0139-word-break
0229-majority-element-ii
0438-find-all-anagrams-in-a-string
0442-find-all-duplicates-in-an-array
0491-non-decreasing-subsequences
0567-permutation-in-string
0594-longest-harmonious-subsequence
0925-construct-binary-tree-from-preorder-and-postorder-traversal
0929-groups-of-special-equivalent-strings
0940-fruit-into-baskets
0952-word-subsets
1016-subarray-sums-divisible-by-k
1029-vertical-order-traversal-of-a-binary-tree
1043-grid-illumination
1423-maximum-number-of-occurrences-of-a-substring
1526-html-entity-parser
1557-check-if-a-string-contains-all-binary-codes-of-size-k
1987-substrings-of-size-three-with-distinct-characters
1995-finding-pairs-with-a-certain-sum
2270-find-all-lonely-numbers-in-the-array
2388-replace-elements-in-an-array
2696-the-number-of-beautiful-subsets
3034-points-that-intersect-with-cars
3299-find-the-maximum-number-of-elements-in-subset
3335-minimum-operations-to-write-the-letter-y-on-a-grid
3405-count-the-number-of-special-characters-ii
3420-find-occurrences-of-an-element-in-an-array

Sliding Window

0030-substring-with-concatenation-of-all-words
0438-find-all-anagrams-in-a-string
0567-permutation-in-string
0594-longest-harmonious-subsequence
0643-maximum-average-subarray-i
0713-subarray-product-less-than-k
0940-fruit-into-baskets
1046-max-consecutive-ones-iii
1138-grumpy-bookstore-owner
1423-maximum-number-of-occurrences-of-a-substring
1445-number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
1567-maximum-number-of-vowels-in-a-substring-of-given-length
1987-substrings-of-size-three-with-distinct-characters
2211-k-radius-subarray-averages
3743-reschedule-meetings-for-maximum-free-time-i

Sorting

0015-3sum
0016-3sum-closest
0018-4sum
0075-sort-colors
0229-majority-element-ii
0594-longest-harmonious-subsequence
0929-groups-of-special-equivalent-strings
1029-vertical-order-traversal-of-a-binary-tree
1184-car-pooling
1253-sort-the-matrix-diagonally
1478-maximum-number-of-events-that-can-be-attended
1851-maximum-number-of-events-that-can-be-attended-ii
2290-removing-minimum-number-of-magic-beans
2696-the-number-of-beautiful-subsets

Counting

0229-majority-element-ii
0594-longest-harmonious-subsequence
1983-maximum-population-year
1987-substrings-of-size-three-with-distinct-characters
2270-find-all-lonely-numbers-in-the-array
3335-minimum-operations-to-write-the-letter-y-on-a-grid

Two Pointers

0011-container-with-most-water
0015-3sum
0016-3sum-closest
0018-4sum
0031-next-permutation
0075-sort-colors
0125-valid-palindrome
0151-reverse-words-in-a-string
0167-two-sum-ii-input-array-is-sorted
0345-reverse-vowels-of-a-string
0443-string-compression
0556-next-greater-element-iii
0557-reverse-words-in-a-string-iii
0567-permutation-in-string
0680-valid-palindrome-ii
1850-minimum-length-of-string-after-deleting-similar-ends
1880-largest-merge-of-two-strings
1972-rotating-the-box
2128-reverse-prefix-of-word
2228-watering-plants-ii
2816-lexicographically-smallest-palindrome
3018-make-string-a-subsequence-using-cyclic-increments

Binary Search

0167-two-sum-ii-input-array-is-sorted
0222-count-complete-tree-nodes
0713-subarray-product-less-than-k
0729-my-calendar-i
0731-my-calendar-ii
0732-my-calendar-iii
1046-max-consecutive-ones-iii
1851-maximum-number-of-events-that-can-be-attended-ii

Greedy

0011-container-with-most-water
0680-valid-palindrome-ii
0825-max-increase-to-keep-city-skyline
1285-balance-a-binary-search-tree
1478-maximum-number-of-events-that-can-be-attended
1711-find-valid-matrix-given-row-and-column-sums
1880-largest-merge-of-two-strings
2290-removing-minimum-number-of-magic-beans
2816-lexicographically-smallest-palindrome
3743-reschedule-meetings-for-maximum-free-time-i

Simulation

0289-game-of-life
1184-car-pooling
1310-watering-plants
1324-where-will-the-ball-fall
1342-queens-that-can-attack-the-king
1386-shift-2d-grid
2132-convert-1d-array-into-2d-array
2228-watering-plants-ii
2388-replace-elements-in-an-array
3215-matrix-similarity-after-cyclic-shifts
3600-find-the-k-th-character-in-string-game-i

String

0012-integer-to-roman
0030-substring-with-concatenation-of-all-words
0125-valid-palindrome
0139-word-break
0151-reverse-words-in-a-string
0224-basic-calculator
0241-different-ways-to-add-parentheses
0257-binary-tree-paths
0345-reverse-vowels-of-a-string
0438-find-all-anagrams-in-a-string
0443-string-compression
0449-serialize-and-deserialize-bst
0556-next-greater-element-iii
0557-reverse-words-in-a-string-iii
0567-permutation-in-string
0680-valid-palindrome-ii
0929-groups-of-special-equivalent-strings
0952-word-subsets
1423-maximum-number-of-occurrences-of-a-substring
1526-html-entity-parser
1557-check-if-a-string-contains-all-binary-codes-of-size-k
1567-maximum-number-of-vowels-in-a-substring-of-given-length
1850-minimum-length-of-string-after-deleting-similar-ends
1880-largest-merge-of-two-strings
1987-substrings-of-size-three-with-distinct-characters
2128-reverse-prefix-of-word
2217-step-by-step-directions-from-a-binary-tree-node-to-another
2244-number-of-laser-beams-in-a-bank
2465-shifting-letters-ii
2576-minimum-penalty-for-a-shop
2691-count-vowel-strings-in-ranges
2816-lexicographically-smallest-palindrome
3018-make-string-a-subsequence-using-cyclic-increments
3396-valid-word
3405-count-the-number-of-special-characters-ii
3617-find-the-original-typed-string-i
3618-find-the-original-typed-string-ii

Math

0012-integer-to-roman
0060-permutation-sequence
0224-basic-calculator
0231-power-of-two
0241-different-ways-to-add-parentheses
0486-predict-the-winner
0556-next-greater-element-iii
1477-product-of-the-last-k-numbers
1787-sum-of-absolute-differences-in-a-sorted-array
2244-number-of-laser-beams-in-a-bank
2696-the-number-of-beautiful-subsets
3215-matrix-similarity-after-cyclic-shifts
3600-find-the-k-th-character-in-string-game-i
3601-find-the-k-th-character-in-string-game-ii

Stack

0224-basic-calculator
2128-reverse-prefix-of-word

Dynamic Programming

0139-word-break
0241-different-ways-to-add-parentheses
0486-predict-the-winner
0494-target-sum
1851-maximum-number-of-events-that-can-be-attended-ii
2078-maximum-compatibility-score-sum
2205-find-good-days-to-rob-the-bank
2504-find-all-good-indices
2696-the-number-of-beautiful-subsets
3618-find-the-original-typed-string-ii

Prefix Sum

0238-product-of-array-except-self
0713-subarray-product-less-than-k
0731-my-calendar-ii
0732-my-calendar-iii
1016-subarray-sums-divisible-by-k
1046-max-consecutive-ones-iii
1184-car-pooling
1477-product-of-the-last-k-numbers
1787-sum-of-absolute-differences-in-a-sorted-array
1983-maximum-population-year
2205-find-good-days-to-rob-the-bank
2290-removing-minimum-number-of-magic-beans
2465-shifting-letters-ii
2504-find-all-good-indices
2576-minimum-penalty-for-a-shop
2691-count-vowel-strings-in-ranges
2714-left-and-right-sum-differences
3034-points-that-intersect-with-cars
3338-count-submatrices-with-top-left-element-and-sum-less-than-k
3618-find-the-original-typed-string-ii

Bit Manipulation

0090-subsets-ii
0222-count-complete-tree-nodes
0231-power-of-two
0491-non-decreasing-subsequences
1557-check-if-a-string-contains-all-binary-codes-of-size-k
2078-maximum-compatibility-score-sum
3600-find-the-k-th-character-in-string-game-i
3601-find-the-k-th-character-in-string-game-ii

Recursion

0060-permutation-sequence
0224-basic-calculator
0231-power-of-two
0241-different-ways-to-add-parentheses
0486-predict-the-winner
3600-find-the-k-th-character-in-string-game-i
3601-find-the-k-th-character-in-string-game-ii

Design

0449-serialize-and-deserialize-bst
0729-my-calendar-i
0731-my-calendar-ii
0732-my-calendar-iii
1477-product-of-the-last-k-numbers
1572-subrectangle-queries
1995-finding-pairs-with-a-certain-sum

Data Stream

1477-product-of-the-last-k-numbers

Enumeration

2080-check-if-move-is-legal
2290-removing-minimum-number-of-magic-beans
3299-find-the-maximum-number-of-elements-in-subset
3398-make-a-square-with-the-same-color

Heap (Priority Queue)

1184-car-pooling
1478-maximum-number-of-events-that-can-be-attended
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit

Segment Tree

0729-my-calendar-i
0731-my-calendar-ii
0732-my-calendar-iii
0880-rectangle-area-ii

Ordered Set

0729-my-calendar-i
0731-my-calendar-ii
0732-my-calendar-iii
0880-rectangle-area-ii
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit

Line Sweep

0391-perfect-rectangle
0880-rectangle-area-ii

Matrix

0036-valid-sudoku
0037-sudoku-solver
0073-set-matrix-zeroes
0289-game-of-life
0810-valid-tic-tac-toe-state
0825-max-increase-to-keep-city-skyline
1253-sort-the-matrix-diagonally
1324-where-will-the-ball-fall
1342-queens-that-can-attack-the-king
1386-shift-2d-grid
1572-subrectangle-queries
1711-find-valid-matrix-given-row-and-column-sums
1972-rotating-the-box
2080-check-if-move-is-legal
2132-convert-1d-array-into-2d-array
2244-number-of-laser-beams-in-a-bank
2398-check-if-matrix-is-x-matrix
3215-matrix-similarity-after-cyclic-shifts
3335-minimum-operations-to-write-the-letter-y-on-a-grid
3338-count-submatrices-with-top-left-element-and-sum-less-than-k
3398-make-a-square-with-the-same-color
3461-find-the-minimum-area-to-cover-all-ones-i

Rolling Hash

1557-check-if-a-string-contains-all-binary-codes-of-size-k

Hash Function

0572-subtree-of-another-tree
1557-check-if-a-string-contains-all-binary-codes-of-size-k

Queue

1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit

Monotonic Queue

1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit

Game Theory

0486-predict-the-winner

Memoization

0139-word-break
0241-different-ways-to-add-parentheses

Backtracking

0037-sudoku-solver
0051-n-queens
0052-n-queens-ii
0077-combinations
0090-subsets-ii
0113-path-sum-ii
0257-binary-tree-paths
0491-non-decreasing-subsequences
0494-target-sum
1007-numbers-with-same-consecutive-differences
2078-maximum-compatibility-score-sum
2696-the-number-of-beautiful-subsets

Bitmask

2078-maximum-compatibility-score-sum

Breadth-First Search

0101-symmetric-tree
0111-minimum-depth-of-binary-tree
0199-binary-tree-right-side-view
0449-serialize-and-deserialize-bst
0998-check-completeness-of-a-binary-tree
1007-numbers-with-same-consecutive-differences
1029-vertical-order-traversal-of-a-binary-tree

Combinatorics

2696-the-number-of-beautiful-subsets

Trie

0139-word-break

Tree

0101-symmetric-tree
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0109-convert-sorted-list-to-binary-search-tree
0111-minimum-depth-of-binary-tree
0113-path-sum-ii
0129-sum-root-to-leaf-numbers
0199-binary-tree-right-side-view
0222-count-complete-tree-nodes
0230-kth-smallest-element-in-a-bst
0257-binary-tree-paths
0437-path-sum-iii
0449-serialize-and-deserialize-bst
0538-convert-bst-to-greater-tree
0572-subtree-of-another-tree
0669-trim-a-binary-search-tree
0925-construct-binary-tree-from-preorder-and-postorder-traversal
0998-check-completeness-of-a-binary-tree
1029-vertical-order-traversal-of-a-binary-tree
1285-balance-a-binary-search-tree
2217-step-by-step-directions-from-a-binary-tree-node-to-another

Depth-First Search

0101-symmetric-tree
0111-minimum-depth-of-binary-tree
0113-path-sum-ii
0129-sum-root-to-leaf-numbers
0199-binary-tree-right-side-view
0230-kth-smallest-element-in-a-bst
0257-binary-tree-paths
0437-path-sum-iii
0449-serialize-and-deserialize-bst
0538-convert-bst-to-greater-tree
0572-subtree-of-another-tree
0669-trim-a-binary-search-tree
1029-vertical-order-traversal-of-a-binary-tree
1285-balance-a-binary-search-tree
2217-step-by-step-directions-from-a-binary-tree-node-to-another

Binary Tree

0101-symmetric-tree
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0109-convert-sorted-list-to-binary-search-tree
0111-minimum-depth-of-binary-tree
0113-path-sum-ii
0129-sum-root-to-leaf-numbers
0199-binary-tree-right-side-view
0222-count-complete-tree-nodes
0230-kth-smallest-element-in-a-bst
0257-binary-tree-paths
0437-path-sum-iii
0449-serialize-and-deserialize-bst
0538-convert-bst-to-greater-tree
0572-subtree-of-another-tree
0669-trim-a-binary-search-tree
0925-construct-binary-tree-from-preorder-and-postorder-traversal
0998-check-completeness-of-a-binary-tree
1029-vertical-order-traversal-of-a-binary-tree
1285-balance-a-binary-search-tree
2217-step-by-step-directions-from-a-binary-tree-node-to-another

String Matching

0572-subtree-of-another-tree

Divide and Conquer

0105-construct-binary-tree-from-preorder-and-inorder-traversal
0109-convert-sorted-list-to-binary-search-tree
0925-construct-binary-tree-from-preorder-and-postorder-traversal
1285-balance-a-binary-search-tree

Linked List

0109-convert-sorted-list-to-binary-search-tree

Binary Search Tree

0109-convert-sorted-list-to-binary-search-tree
0230-kth-smallest-element-in-a-bst
0449-serialize-and-deserialize-bst
0538-convert-bst-to-greater-tree
0669-trim-a-binary-search-tree
1285-balance-a-binary-search-tree